Brain-correlates of processing local dependencies within a statistical learning paradigm

Mismatch negativity predicts age-related declines in memory precision

Does precision in auditory perception predict precision in subsequent memory (i.e., mnemonic discrimination) in aging? This study examined if the mismatch negativity (MMN), an electrophysiological marker of change detection and encoding, relates to age differences in mnemonic discrimination. The MMN was recorded in 92 adults (18-86 years, 47 females) in a passive oddball paradigm using tone sequences. Participants then completed a surprise recognition test for presented sequences (i.e., old targets) against novel sequences (i.e., similar lures and dissimilar foils). Across the adult lifespan, MMN amplitudes showed attenuation with increasing age, accompanied by worse performance discriminating targets from lures and foils. Across participants, smaller MMN amplitude predicted worse recognition performance. Notably, MMN amplitude partially explained age-related declines in target-lure discriminability, but not target-foil discriminability. Findings reinforce the MMN as a marker of mnemonic discrimination, and clarify how age-related declines in memory precision at retrieval may be explained by age differences at encoding.

Making sense of music: Insights from neurophysiology and connectivity analyses in naturalistic listening conditions

According to the latest frameworks, auditory perception and memory involve the constant prediction of future sound events by the brain, based on the continuous extraction of feature regularities from the environment. The neural hierarchical mechanisms for predictive processes in perception and memory for sounds are typically studied in relation to simple acoustic features in isolated sounds or sound patterns inserted in highly certain contexts. Such studies have identified reliable prediction formation and error signals, e.g., the N100 or the mismatch negativity (MMN) evoked responses. In real life, though, individuals often face situations in which uncertainty prevails and where making sense of sounds becomes a hard challenge. In music, not only deviations from predictions are masterly set up by composers to induce emotions but sometimes the sheer uncertainty of sound scenes is exploited for aesthetic purposes, especially in compositional styles such as Western atonal classical music. In very recent magnetoencephalography (MEG) and electroencephalography (EEG) studies, experimental and technical advances in stimulation paradigms and analysis approaches have permitted the identification of prediction-error responses from highly uncertain, atonal contexts and the extraction of prediction-related responses from real, continuous music. Moreover, functional connectivity analyses revealed the emergence of cortico-hippocampal interactions during the formation of auditory memories for more predictable vs. less predictable patterns. These findings contribute to understanding the general brain mechanisms that enable us to predict even highly uncertain sound environments and to possibly make sense of and appreciate even atonal music.

Neural correlates of statistical learning in developmental dyslexia: An electroencephalography study

The human brain extracts statistical regularities from the surrounding environment in a process called statistical learning. Behavioural evidence suggests that developmental dyslexia affects statistical learning. However, surprisingly few studies have assessed how developmental dyslexia affects the neural processing underlying this type of learning. We used electroencephalography to explore the neural correlates of an important aspect of statistical learning - sensitivity to transitional probabilities - in individuals with developmental dyslexia. Adults diagnosed with developmental dyslexia (n = 17) and controls (n = 19) were exposed to a continuous stream of sound triplets. Every so often, a triplet ending had a low transitional probability given the triplet's first two sounds ("statistical deviants"). Furthermore, every so often a triplet ending was presented from a deviant location ("acoustic deviants"). We examined mismatch negativity elicited by statistical deviants (sMMN), and MMN elicited by location deviants (i.e., acoustic changes). Acoustic deviants elicited a MMN which was larger in the control group than in the developmental dyslexia group. Statistical deviants elicited a small, yet significant, sMMN in the control group, but not in the developmental dyslexia group. However, the difference between the groups was not significant. Our findings indicate that the neural mechanisms underlying pre-attentive acoustic change detection and implicit statistical auditory learning are both affected in developmental dyslexia.